Cutting edge: lymphoproliferative disease in the absence of CTLA-4 is not T cell autonomous.

Mice deficient for the expression of CTLA-4 develop a lethal lymphoproliferative syndrome and multiorgan inflammation leading to death at about 4 wk of age. Here we show that RAG2-deficient mice reconstituted with CTLA-4-deficient bone marrow do not develop a lymphoproliferative syndrome despite lymphocyte infiltration mainly into pericardium and liver. Moreover, RAG2-deficient mice reconstituted with a mixture of normal and CTLA-4-deficient bone marrow remain healthy and do not develop any disease. Thus, the lethal disease observed in CTLA-4-deficient mice is not T cell autonomous and can be prevented by factors produced by normal T cells.     

Partial purification and properties of a chromatin bound endonuclease from the marine sponge Geodia cydonium

A chromatin bound endonuclease (Mr:107,000) has been extracted and partially purified from the siliceous sponge Geodia cydonium. Disc gel electrophoresis showed that only one enzyme was present in the partially purified preparation which was able to degrade DNA and poly(A). The enzyme liberates oligonucleotides on incubation with poly(A), which are further degraded to yield the 5'-mononucleotide, which has a pI of 6.5 and a pH optimum of 7.5-8.0. Cations are not required for enzymic activity and EDTA does not inhibit the enzyme. Only iodosobenzoic acid was found to completely inhibit the enzyme. The enzyme hydrolysed poly(A), poly(U), poly(C), DNA, poly[d(A-T)], poly[d(G-C)], but not poly (dA) or poly(G).